Additionally say the roads are shot and will need replacing, you may have to make an adjustment on that. 

"Must have 3X monthly rent in pre-tax income and a 650+ credit score"  In addition, I have the applicants pay the $30-$40 fee to have me use the following website "https://biggerpockets.mysmartmove.com/" to screen their credit. 

It may seem like demanding criteria, but I will not get into a deal to lose money, and I won't have the additional expense of property managers, I'll be self managing.

Congrats on your new addition and good luck with it.

Did you do an addition, or did it have unfinished space? 

Additionally the HVAC in the attic has a Freon leak and the internals of the unit were replaced under warranty thankfully.

For these properties the 10 day grace period has been helpful.My lease specifies "...If you pay less than the full balance due, payments will be applied first to the earliest unpaid rent and other additional rent charges."  

For some additional information.

IE- more stable income, more tenant references, and the biggest reason-they are willing to pay an additional non refundable fee for their pet. 

You'd need an independent cost analysis on the replacement (I'd get three estimates), permission from the city to close as a variance to their permitting process (likely the sticking point) and a new addendum for this additional agreement.